The background description provided herein is for the purpose of generally presenting the context of the disclosure. Unless otherwise indicated herein, the materials described in this section are not prior art to the claims in this application and are not admitted to be prior art by inclusion in this section.
In-Die Variation (IDV) naturally produces multi-core processors with some cores that are better (higher performance or lower voltage) than others. Enumeration and use of these cores in accordance with their native capability may provide upside turbo performance that can be realized and marketed. Some multi-core processors, such Intel® x64 multi-core processors, identify the cores that can run at frequencies higher than a standard frequency range. For the x64 multi-core processors, these identified higher performance cores are called Favored Cores, and the hardware feature is called Asymmetric Core Turbo (ACT).
Existing operating system (OS) software is not aware of this implicit heterogeneity in the performance capability of the various cores. Thus, to exploit the feature, a system administrator has to use a white list to manually identify important, performance sensitive or otherwise high priority execution threads, and a driver is employed to establish affinity between the threads in the white list and the Favored Cores.
The main disadvantage is that the administrator needs to keep updating the white-list for different scenarios/workloads, which is not a scalable solution at all. Also, often user applications could establish affinity for other workloads (not in the white list) with the Favored Cores, thereby causing adverse performance impacts.